Carb cfm with ported heads?

My brother pickup 2 tenths going from 2.5 to 3 inch exhaust with a 408



So you think now the exhaust will be the choke point?
My exhaust guy won't do 3" over the axles. That and the 3.23's are pretty much non-negotiable. Mainly a street car, but would like to crack 11's at the track.
Will the 750 hold me back with the added flow? I want a bigger carb, but do I really need one?[/QUOTe